During the last year two new methods have been developed. First, a modified protocol of our ALFA histofluorescence method, permitting highly sensitive studies of the early development of the central catecholamine systems. Second, a new method for intracerebral grafting of suspensions of dissociated embryonic central neurons. The proposed work will be carried out along three lines: 1) Further development of the fluorescence histochemical methodology with respect to secondary and tertiary indolamines, such as melatonin and bufotenin. 2) Ontogenetic and neuroanatomical studies of the central catecholamine systems, with special reference to recently discovered hyperinnervation phenomena during early stages of development. 3) To further develop our new intracerebral transplantation technique with special reference to the possibilities of using this approach as a new tool for the analysis of monoaminergic functions in the CNS. During the last year we have shown that many types of central neurons can be grafted with a stereotaxic technique to a variety of brain sites. The morphological and behavioral consequences of such grafts will now be analyzed in detail.